1. Field of the Invention
The present invention relates to ruthenium-, nickel- and/or cobalt-containing catalysts which can be used for aminating alkylene oxides, alcohols, aldehydes and ketones. The present invention furthermore relates to processes for the preparation of the catalysts, the use thereof in amination reactions and processes for the preparation of amination products.
2. Description of Related Art
EP-A-0 146 508 discloses dehydrogenation/hydrogenation catalysts which contain ruthenium, nickel and/or cobalt. The catalysts used contain about 0.25-1.0% by weight of ruthenium and 7.5 or 10% by weight of nickel or 10% by weight of cobalt or 4% by weight of nickel and 4% by weight of cobalt, based on the total weight of the catalyst, on an alumina carrier. In addition to nickel, the catalysts may also contain copper and chromium in addition to nickel, and also iron in addition to nickel and cobalt. The ruthenium is applied to the catalyst in the form of a solution of a ruthenium halide. The catalyst is used, for example, for aminating monoethanolamine with ammonia, the reaction being carried out in an autoclave.
EP-A-0 254 335 discloses a process for the preparation of a hydrogenation and/or dehydrogenation catalyst, about 10% by weight of nickel or cobalt and about 0.5% by weight of ruthenium, based on the total weight of the catalyst, being applied to an alumina carrier. The catalyst is prepared by impregnating the carrier with a nickel nitrate or cobalt nitrate solution, then impregnating with aqueous hydrochloric acid and subsequently impregnating with a solution of ruthenium nitrosyl nitrate. A ruthenium halide is not used for coating the carrier. The catalyst is used for reacting monoethanolamine with ammonia in an autoclave.
The known catalysts have high contents of nickel and/or cobalt. Furthermore, the stability is insufficient, particularly in the case of the catalysts described in EP-A-0 254 335. The selectivities with respect to ethylenediamine which are obtained in the reaction of monoethanolamine with ammonia are insufficient in the continuous procedure.